RESUMEN
A simple and rapid method was established for the determination of the content of L-malic acid in fermentation liquor. This procedure includes six steps: (1) Use a microi- njector to inject the fermentation liquor quantitively on the filter paper, then use the chromatography solution (n-butanol: formic acid: water=8:1.5:1) for paper chromatography. (2) Atomize the display reagent (10ml 0.02?10~(-2) bromocresol green: 0.2ml 10?10~(-2) sodium hydroxide) on the chromatography paper. (3) Scissor off L-malic acid spots from the paper and put in into 5 ml distilled water for three hours. (4) In 1ml eluent, add 6 ml 96?10~(-2) sulphuric acid and 0.1ml 1.0?10~(-2) ?-naphthol.(5) Heat the reaction system in 100℃ water for sixty minutes. (6) After cooling determine the optical density at the wavelength 476 am in the colorimeter.